Method and apparatus for controlling the crankcase pressure in internal-combustion engines



Patented Sept. 30, 1952 METHOD AND APPARATUS FOR CONTROL LING THE CRANKCASE PRESSURE IN IN- TERNAL-COMBUSTION ENGINES FrancisAlWard, Cambridge, Mass., assignor to John B. Howard, trustee, Marblehead, Mass.

j Application 'Aprill, 1950, Serial No. 153,434

' 8 Claims. (01. 123-119) In internal combustion engines the hot gases which blow by the piston rings condense upon contact'with the colder engine parts and form water and acids which in combination with the oil, dirt and vapors create sludge which tends to block oil passages in the piston ring grooves, bearings, Journals and other vital engine parts. The gases and impurities contacting the high temperature portions of the engine, such as the pistons, rings and valves, bake to a hard varnish which" causes sticking and malfunctioning of these parts.

Objects of thisinventicn are to provide both a method *and apparatus which exhaust the crankcase (including all interccmmunicating parts) 'of an internal combustion engine, which prevent dirt from entering the crankcase, which remove the gases and vapors from the crankcase when the engine is idling or lightly loaded, which eliminate objectionable fumes, which greatly reduce the formation of sludge, which do not interfere with the lubrication of the cylinder walls, which materially lengthen the life of the engine, which increase the power delivered by the engine, which reduce the oil and gasoline consumption of the engine, which prevent etching of the valve springs and other vital engine .parts, which are. automatic in operation, which are reliable and troublefree, which are simple and economical to construct, which can be easily incorporated in new engine designs or installed upon existing eng'ines, which do not interfere with the normal operation of the engine and. which generally advanvethe art to which they are related.

-In one principal aspect'the invention involves the method of controlling crankcase pressure in internal combustion engines which comprises the steps of substantially sealing all crankcase openings such as the oil filler and measuring bayonet openings from the atmosphere and interconnecting the engine intake manifold or other portion maintained at a negative pressure by the engine operation to the crankcase so that the vapors and gases are withdrawn from the crankcase into the manifold; thence through the combustion chambers'and out the exhaust pipe. The relative flow of gas from the crankcase into the manifold and the flow of gases into the crankcase due to atmospheric leakage by the seals and piston blowby is regulated, for example, bythrottling the gas how to the manifold, so that the lower manifold pressure at light loads causes substantially lower pressure in the crankcase than atmospheric I pressure. L

the following description andinto the crankcase l4 through a tube [15* I 2 i so that, with the engine idling, approximately: one-half an atmosphere of pressure results in the crankcase, thereby producing the maximum exhaust effect when it is needed most, and with the engine under heavy load the crankcase pres-. sure rises substantially to ambient pressure or higher to provide added lubrication of the cylinder walls by the oil drawn up upon the walls by the pressure differential above and below the pistons. v. In another principal aspect theinvention contemplates means for closing the external openings into the crankcase, including timing gear case or chain case and valve chambers so that the interior of the crankcase is substantially sealed from the atmosphere. Conduit or other means interconnect the crankcase with the en-' gine intake manifold to reduce thepressure in the crankcase below atmospheric pressure when the engine is idling or lightly loaded and the manifold pressure is at a minimum. Regulating means, such as a valve or orifice, are located in the conduit means to limit the flow of gases through the conduit so that as the load increases the ratio of leakage into the crankcase to the' outflow of gases from the crankcase increases and the pressure in the crankcase rises. Further objects related to various features of construction will be apparent from a consideration' of accompanying drawing where I Fig. l is a side elevation of an engine incorpo-- rating the invention; I I

Fig. .2 is a front elevation view of the engine shown in Fig. 1;

Fig. 3 is a sectional view showing the details of the metering valve; 7 I Fig. 4 is a sectional view on line 1-4 of Fig. 3&

and

Fig. 5 is a sectional view showing the manner in which the oil bayonet of the engine is sealed.-- Referring to Figs. 1 and 2, the numeral in designates an internal combustion engine. 'Ihe engine is of any conventional design having an intake manifold l l acting as a conduit connecting the carburetor l2 with the intake valves which conform to standard practice and are not material to the present invention. The engine is also provided with an oil filler pipe I3 communicat ing with a crankcase 14 which acts as a-reservoir' for the lubricating oil supply. The oil level'in the crankcase I4 is measured by means of abayonet or dip stick I6 which projects downwardly In carrying out the inventionpthe" crankcase boredin one end of the bar stock. The opposite. end is'provided with an aperture throughwhich. is inserted the bayonet I6. Theseal ismadeby. a washer 22 of oil resistant yieldablezmaterial such as leather or neoprene. The washer 22 is compressed between the top of the tube l1" and. When a vacuum is created in the crankcase l l as. de-- the bottom of the recess in cap-20.-

scribed below, the difierence in pressure above and below the cap helps to hold it tightly-in place. The conventional draft tube which is ordinaril used toprovide; ventilation of the crankcase I Azis replacedby f a compression fitting One-rend of a conduit such as the. The op pQsite entitofathe tube 26 is securedto a meter-- 244F131: 1 tubing-;. 2 6.; is secured inthe fitting v 2 4.

ing valve-3E by means of avsimilar fitting 25-.

The, detailsgofi construction of the metering valve 3ll -arei shown in-Fi s. 3. and 4.. The valve comprisesa body 32- machined from a short length of hex bar stock. Extending through the body isan-aperture 34. Oneend of the aperture 34-ais threadedto, accommodate the threaded end, of, the compression fitting 2'8; connecting the, The oppositeend of the ap erture-M; is.- counterbored to receive the, flange tubing 26.- (Fig. l)

42..o f-. the pin l!)v projects downwardly into the.

aperturein the fitting-ifi'thereby to restrict par-: tially. the, aperture. The amount of restriction provided by the shank 42 is adjustable by moving :thezscrew 40 in or out..

,Asgis; shown inliig, 4:, anintegralbcss i6. is

providedzupon the rear of thevalve body 32. The

boss-dmhas. an internally threaded aperture 48' interconnecting with the aperture 35. Each of the hexfaces adjoining the face, carrying. the bushing 36 are also provided with threaded apertures. 58 ;which interconnect with the aperture 34. These apertures 51! are provided. as convenient connections for. a vacuum Windshield wiper or other use. When not being-soemployed, the apertures 58- are closed bymeans of the screw plugs 52.

The: valve. 30 is connected to and supported from theengine intake manifold I lby means of a.close nipple 54. (Fig. 4) Oneendof the-nipple 54 is threadedinto-the boss Q6.- Theother end of; the nipple. 54 engages the manifold aperture. provided for the connection to vacuum wind.- shield wipers ;or' other. threaded aperture tapped intofthemanifold i I orin communication there- As; will be.readily appreciated from the above, the. vacuum createdin" the intake manifold ll bygtheoperation of the engine I ll creates a partilsvacuuminthefcrankcase i l exhausting the.-

moisture. and. gases-or other matterblown by the piston rings. Because. of thesealing of; the crankcase; i l; to the. atmosphere there-.-is no function of both the negative pressure in the intake manifold. andthe resistance to the flow ofieredbytheconduit and the valve 30.

Themostsatisfactory setting of the screw 40 of the valve 30 has been found to be that setting whichrestrictsthefiow from the crankcase [4 so thatanegative pressure of approximately onehalf anatmosphere is created in the crankcase when the engine Ill is operating at idling speedunder no load. For a new engine with normal compression a negative pressure of 13 inches-0f: mercury; has been found to be satisfactory. With-sucha negative pressuretthe-idifference of pressure-above-and below thepiston rings is greatly reduced. so that oil does not work past the rings into: the combustion chamber. Vapors and gases are exhaustedfrom the crank-.- case- M. so that they arenot present. to combine withother elements to formsludge and. varnishupon, or-to etch, the. internal engineparts.

As. the. load. imposed upon the .engine is, in'- creased thenegative pressure; in;theintake manie fold decreases so that the flow of gases a-ndvapor-e through. thev conduit .28; is also decreased. The increase. in pressure inthe; crankcase increases: the; difference. of pressure aboveand below the,

piston. rings. sothaton'. the intake. strokes-1011. flows upto lubricate the. cylinder walls during.

heavy load, conditions when the, need -for the lubricant is greatest.

This: apparatus is unique in. that thecrankcase.

is. completely sealed and; asubstantial; vacuum. isv created in. the. crankcasev through a suction,

pipe leading. to-the. intake. manifold, the pipe,

containing a. constant-position,valve, set to produce .maximum. vacuum in. the, crankcase when. the butterfly valve ispclosedand therefore. when-z needed most to preventoil frombeing draWnup,

ent. invention. the crankcase is, entirely sealed; so. that..only a. negligible amount. ofv air. need be;

withdrawn tomaintaina substantial-vacuum; and no. substantialdraft-is produced in.the. crankcase.

.It' shouldbe understood vthatthev present dis--- closure. is forthepurpose of illustration only and" that this invention includes allmodificationsand equivalents which fall within the scope of. the: appended. claims.

I- claim:

1. In controlling crankcase pressurein internai;

combustion engines,, the method which comprises" the steps of substantially sealing. the crankcase:

from. the atmosphere, interconnecting-the engine I intake manifold and the crankcase so thatggaseszg aredrawn fromthe crankcasayand; adjusting the relative rates of flow of gases into andfrom the crankcase so that the negative pressure within the crankcase substantially to ambient pressure engine is lightly loaded than when the engine is heavily loaded.

2. In controlling crankcase pressure in internal combustion engines, the method which comprises the steps of substantially sealing the crankcase from the atmosphere, interconnecting the engine intake manifold and the crankcase so that gases are drawn from the crankcase, and adjusting the relative rates of flow of gases into and from the crankcase to reduce the pressure Within the crankcase below atmosphere pressure when the engine is lightly loaded and to increase the pressure within the crankcase substantially to atmospheric pressure when the engine is heavily loaded.

3. In controlling crankcase pressure in internal combustion engines, the method which comprises the steps of substantially sealing the crankcase from the atmosphere, interconnecting the engine intake manifold and the crankcase so that gases are drawn from the crankcase, and adjusting the relative rates of flow Of gases into and from the crankcase to reduce the pressure within the crankcase to approximately one-half an atmosphere below ambient pressure when the engine is lightly loaded and to increase the pressure within the crankcase substantially to ambient pressure when the engine is heavily loaded.

4. For use with an internal combustion engine having an intake manifold and a crankcase acte ing as a reservoir for the lubricating oil supply, means for substantially sealing the interior of the crankcase from the atmosphere, conduit means interconnecting. the manifold and the crankcase to reduce the pressure in the crankcase below atmospheric pressure when the engine is lightly loaded, and restricting means located in the conduit means for limiting the flow of gases through the conduit means to less than the leakage into the crankcase when the load upon the engine is increased.

5. For use with an internal combustion engine having an intake manifold and a crankcase acting as a reservoir for the lubricating oil supply, means for substantially sealing the interior of the crankcase from the atmosphere, conduit means interconnecting the manifold and the crankcase to reduce the pressure in the crankcase below atmospheric pressure when the engine is lightly loaded, said conduit means including a restricted portion of constant size at all loads for limiting the flow of gases through the conduit means to less than the leakage into the crankcase when the load upon the engine is increased.

6. For use with an internal combustion engine having an intake manifold and a crankcase acting as a reservoir for the lubricating oil supply, means for substantially sealing the interior of the crankcase from the atmosphere, a conduit interconnecting the manifold and the crankcase to reduce the pressure in the crankcase below atmospheric pressure when the engine is lightly loaded, and a constant-position valve located in the conduit for limiting the flow of gases through the conduit means to less than the leakageinto the crankcase when the load upon the engine is increased.

7. For use with an internal combustion engine having an intake manifold and a crankcase acting as a reservoir for the lubricating oil supply, means for sealing the dip stick and oil inlet openings to the crankcase, a conduit having one end connected to the rear vent, opening in the engine, and a constant-position valve connected between the interior of the manifold and the other end of the conduit to reduce the pressure in the crankcase below atmospheric pressure when the engine is lightly loaded for limiting the flow of gases through the conduit to less than the leakage into the crankcase when the load upon the engineis increased.

8. For use with an internal combustion engine having an intake manifold containing a butterfly valve and a crankcase acting as a reservoir for the lubricating oil supply, means for substantially sealing the interior of the crankcase from the atmosphere, conduit means interconmeeting the manifold and the crankcase to reduce the pressure in the crankcase below atmospheric pressure when the engine is lightly loaded, and a constant-position valve to restrict the flow of gases through said conduit means, and means to set the valve to produce maximum vacuum in the crankcase when said butterfly valve is closed.

FRANCIS ALWARD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

